Posting Messages
You can post messages in two ways; by creating a new posting,
  or by replying to an existing posting.
New Posting
You can create a new message to post at any time by using the
  "Post Message" menu icon at the top of the screen. It will fill
  in as much information for you as possible, but you should
  always double check this information. Type your message text
  into the "Message" area, and click on the "Post Article" button
  to submit your posting.
Reply to a Posting
When reading a message, there will appear a menu at the top of
  the message area with various links, including a "Post Reply"
  link. You can use this link to post a reply to the current
  message. It will automatically fill in as much information as
  possible, including a "quoted" copy of the message you are
  replying to in the "Message" area. You should double check the
  pre-filled fields, edit the included message for brevity, add
  your reply text, and then click the "Post Article" button to
  submit your posting.